Using anonymous pipes for jobserver support has some advantages:
for example there is nothing on disk that needs to be cleaned up.
However it has many obscure problems, related to the fact that in
order for it to work we need to ensure these resources are properly
passed through to child processes that want to use the jobserver.
At the same time we don't want to pass the pipe to process which
DON'T know about the jobserver.
Other processes can open file descriptors which we then think are
our jobserver, but aren't. And, we open the pipe file descriptors
in blocking mode which doesn't work for all users.
See issues such as SV 57178, SV 57242, and SV 62397
To avoid these issues, use named pipes (on systems where they are
available) instead of anonoymous pipes. This simplifies many things:
we never need to pass open file descriptors to our children; they
can open the jobserver named pipe. We don't need to worry about
recursive vs. non-recursive children. Users don't have to "pass
through" the resources if they are invoking sub-makes. Each child
can open its own file descriptor and set blocking as needed.
The downside is the named pipe exists on disk and so must be cleaned
up when the "top-level" make instance exits.
In order to allow make to continue to be used in build systems where
older versions of GNU make, or other tools that want to use the
jobserver, but don't understand named pipes, introduce a new option
--jobserver-style that allows the user to choose anonymous pipes.
* NEWS: Announce the change and the --jobserver-style option.
* doc/make.1: Add --jobserver-style documentation.
* doc/make.texi (Special Variables): Add missing items to .FEATURES.
(Options Summary): Add --jobserver-style.
(POSIX Jobserver): Named pipes, changes to --jobserver-auth, and the
--jobserver-style option.
(Windows Jobserver): Document --jobserver-style for Windows.
* configure.ac: Check for mkfifo.
* src/config.h-vms.template: Undefined HAVE_MKFIFO.
* src/config.h.W32.template: Ditto.
* src/main.c: Add jobserver-style as a new command line option.
(main): Add jobserver-fifo to .FEATURES if supported. Pass the style
option to jobserver_setup().
* src/os.h (jobserver_setup): Accept a style string option.
* src/posixos.c (enum js_type): Enumeration of the jobserver style.
(js_type): Which style we are currently using.
(fifo_name): The path to the named pipe (if in use).
(jobserver_setup): If no style is given, or "fifo" is given, set up a
named pipe: get a temporary file and use mkfifo() on it, then open it
for reading and writing. If something fails fall back to anonymous
pipes.
(jobserver_parse_auth): Parse jobserver-auth to determine the style.
If we are using a named pipe, open it. If we're using anonymous pipes
ensure they're valid as before.
(jobserver_get_invalid_auth): Don't invalidate the jobserver when
using named pipes.
(jobserver_clear): Clean up memory used for named pipes.
(jobserver_acquire_all): Unlink the named pipe when done.
* src/w32/w32os.c (jobserver_setup): Check the style argument.
* tests/scripts/features/jobserver: Use --jobserver-style to test
the anonymous pipe behavior, and also test named pipe/semaphore
behavior. Check invalid jobserver-style options.
* tests/scripts/functions/shell: Use --jobserver-style to test the
anonymous pipe behavior, and also test named pipe/semaphore
behavior.
Introduce non-deterministic ordering into goal and prerequisite
traversal to help tease out inconsistent failures that may happen
when running in parallel build mode.
Introduce second order into each dependency chain:
1. Existing order is syntactic order reachable via 'dep->next'
2. New order is shuffled order stored as 'dep->shuf' in each 'dep'
When updating goals and prerequisites and '--shuffle' is provided,
use the shuffled order to walk the graph. When automatic variable
are set always use the syntactic order of parameters.
* Makefile.am: Add new src/shuffle.c and src/shuffle.h file.
* build_w32.bat: Ditto.
* builddos.bat: Ditto.
* makefile.com: Ditto.
* po/POTFILES.in: Ditto.
* doc/make.texi: Add documentation for --shuffle.
* doc/make.1: Ditto.
* src/dep.h (DEP): Add the shuf pointer.
* src/filedef.h (struct file): Add was_shuffled flag.
* src/main.c: (shuffle_mode): Global flag for the shuffle mode.
(usage): Add the --shuffle option.
(switches): Ditto.
(main): Set shuffle_mode based on the command line parameter.
Reshuffle prerequisites if requested.
* src/remake.c (update_goal_chain): Walk the shuffled list if enabled.
(update_file_1): Ditto.
* src/shuffle.h: Provide an interface for shuffling prerequisites.
* src/shuffle.c: Implement option parsing and prerequisite shuffling.
* tests/scripts/options/shuffle: Test shuffle option and modes.
Add debug options to print recipes even if they would otherwise be
silent, and to print the reason that a target was considered out of
date.
Modify --trace to simply be a shorthand for --debug=print,why.
* NEWS: Announce changes.
* doc/make.texi (Summary of Options): Document the new options.
* doc/make.1: Ditto.
* src/debug.h: Add new flags DB_PRINT and DB_WHY.
* src/makeint.h: Remove the trace_flag variable.
* src/job.c (start_job_command): Check debug flags not trace_flag.
(new_job): Ditto.
* src/main.c (trace_flag): Make a static variable for switches.
(decode_debug_flags): Set DB_PRINT and DB_WHY if trace_flag is set.
* tests/scripts/variables/GNUMAKEFLAGS: Update known-good messages.
* tests/scripts/variables/MAKEFLAGS: Ditto.
Move the source code (other than glob) into the "src" subdirectory.
Update all scripting and recommendations to support this change.
* *.c, *.h, w32/*: Move to src/
* configure.ac, Makefile.am, maintMakefile: Locate new source files.
* Basic.mk.template, mk/*: Update for new source file locations.
* NEWS, README.DOS.template: Update for new locations.
* build.template, build_w32.bat, builddos.bat: Ditto.
* po/POTFILES.in: Ditto
* tests/run_make_tests.pl, tests/scripts/features/load*: Ditto.
* make.1: Move to doc.
* mk/VMS.mk: Add support for building on VMS (hopefully).
* makefile.vms, prepare_w32.bat: Remove.
* SCOPTIONS: Update to define HAVE_CONFIG_H
